Measuring the State of Canada's Birds

This report presents indicators of the status of Canadian bird populations and the ecosystems on which they depend.

The species

Horned Grebe (Photo: May Haga)

Data were included for all native species of birds that regularly occur in Canada and for which there is sufficient information on the status of the Canadian population over the past 20 or more years. Of the 451 native species that occur regularly in Canada, there were sufficient data for 327 species to be included in at least one of our national indicators. Other species do not yet have adequate monitoring data, although some recently developed monitoring programs, such as nocturnal owl surveys, will provide improved data in the future. Even among the species included, in some cases our best estimate of their population status is highly imprecise and/or based on a small proportion of the Canadian population, particularly for species with their main breeding areas in the Boreal or Arctic.

The regions

The report presents indicators separately for eight major physiographic regions in Canada. These regions reflect major differences across the country in bird habitats, ecosystems and human activities that shape the landscape. For each of the regions, only species that were considered “characteristic” of the region were included, based on the species’ regional-density or the amount of the species’ range in the region, relative to the other regions. For the Oceans region, all seabird species that regularly occur in Canada were considered characteristic.

In each region, indicators for subsets of the characteristic species that reflect the most important bird groups or habitats within the region were calculated. Not all subgroups were displayed in any given region, so some species are only present in the main indicator (i.e., the black line labelled “All species”).

The graphs

These indicators reflect the average population status of major groups of bird species. They were calculated using regional estimates of each species’ population status that reflect the percent change in the population since the first-year when population monitoring data existed for most regions—1970. The indicators are plotted based on the percentage change, with the scale adjusted so that negative changes are visually comparable to the corresponding positive change required to return the indicator to its original value; for example, an indicator that has decreased by 50% (i.e., reduced to ½ its original level) must then increase by 100% (i.e., double) to return to zero.

Bohemian Waxwing (Photo: Nick Saunders)

There is always some uncertainty associated with an indicator. Open circles are used for the indicator in a year if there is more than a 5% chance that the value of the indicator in that year should be on the other side of the zero line.

Averaging across species gives the best overall estimate of the group’s status, but does not necessarily reflect the trends for all species in a group equally well. For example, a stable indicator may reflect a group in which most or all species have stable trends, or it may reflect a group with an equal number of species with large increases and large decreases. For this reason, bar graphs are also presented to show the number of increasing and decreasing species in each indicator, with separate colours for species with population trends in each of five categories from strongly decreasing (> 50% decline) through strongly increasing (>100% increase).